I don’t actually know why certain people have been saying this, they never used to when I first heard about it. Sure, there was maybe one guy saying he had a bad experience with some really creepy HI, but it was because he was expecting it to happen, and put the image in his own mind. Now, I go on youtube and see videos like “The dangers of astral projection!”, “why astral projection is bad for you” and all other such nonsense which is really only created by internet trolls. Like the guy who made the video “The dangers of astral projection” is actually just a 12 year old kid, how could he possibly understand any “dangers” of it when I seriously doubt he understands why astral projection is possible, given his age.
There is nothing scary about the WILD technique. There is nothing scary about astral projection. There are stories of people with bad experiences, yes, but those that are true are few and far between. Those that are true are either caused because of a random occurrence, or the person was so paranoid of having bad HI that they put the thought in their own minds, causing themselves to be scared. Believe me, if your calm through the whole process, nothing will frighten you.
However, I don’t recommend trying the WILD technique at your level of experience. Unless you have had lucid dreams in the past, I wouldn’t say you quite knew the feel of them. The WILD technique also takes time to perfect, and time to modify to your own specifications. This time could deter anyone new to lucid dreaming, it did with me the first time I got into it. I saw the technique, and thought to myself, “alright, that seems to be the one I want to try and perfect first”, but it took me over two weeks and I never got more than the vibrations. Soon, I fell out of the practice, and literally gave up on lucid dreaming altogether, until I actually had a lucid dream simply by thinking about it one night. The feeling of the dream was so immensely overwhelming, it only lasted a few seconds, but it got me onto the path I am today, and I’m grateful for it. At the time of my “revival”, I knew the WILD process would take too long, so I went with the DILD technique, which gave me a few more lucid dreams. I’m still on my “pilgrimage”, but I’m grateful for each dream I’ve been given because of the time I’ve put into the practice, which still hasn’t been too long. Believe me, in the long run, you’ll be glad you saved the WILD technique until later.
However, if you want to prepare for the WILD technique in your future, you could experiment with different wavelengths to help your understanding of the brain and the science behind lucid dreaming. I’d suggest reading up on Theta waves, and maybe listening to a bit of music that involves theta waves during your meditation, if you do meditate. If you don’t, it’s a good practice to get into if you lucid dream, and especially if you astral project.
But I’m happy to see at least some people are looking for answers instead of just “being to scared to try”. 
. It was terrible not being able to move then, but awesome nonetheless!